Tropical ecology and physical edaphology

Tropical ecology and physical edaphology

82 Book reviews Lal, R., Tropical Ecology and Physical Edaphology. Wiley Interscience, 1987. Price: £72.50. To be successful a farming system in the...

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Book reviews

Lal, R., Tropical Ecology and Physical Edaphology. Wiley Interscience, 1987. Price: £72.50. To be successful a farming system in the tropics depends, as elsewhere, on the long-term maintenance of soils in a fit state to support crop growth. All changes of land management affect the soil, but where the change is extreme, as with deforestation in the tropics, the effects can be catastrophic. Nor is there a simple 'rule-of-thumb' solution. Soils, vegetation and climate interact in complex ways, and a farming system that is successful in, say, the South American cerrado is unlikely to be successful in other savanna regions. Interwoven with this complexity are the requirements and traditional practices of people, and the economic conditions under which they live. Scientists have come to recognise the problems that have to be overcome where food production has to increase in order to feed more people and they can offer solutions. What is now needed is that those who plan land development projects take heed of what is known. This book shows what is known about the physical constraints to crop production in the tropics. It contains 16 chapters which are profusely illustrated with Figures (260) and Tables (334). Chapters 1, 15 and 16 are likely to be of most interest to readers of Agricultural Systems. In Chapter 1 Dr Lal compares the actual with the potential agricultural production in the tropics and points to the lack of appropriate technology to develop this potential. In Chapter 15 (69 pages) he compares shifting cultivation with intensive land use and examines the effects of mulching, crop rotations and fallowing, agroforestry, mechanization, pasture management, fertilizers and manures, and management of wet lands. It is well referenced. Chapter 16 summarizes Dr Lal's philosophy that sustainable farming systems require 'ecological agriculture'. He cites shifting cultivation and bush fallow rotations as examples of ecological agriculture at the subsistence farming level. He advocates the use of mulches, mixed cropping and rotations, agroforestry and mixed farming as the required technology for increased and sustainable yields. It would not do justice to the book to omit reference to chapters which give a very thorough treatment of climate, soil physical properties, vegetation, soil fauna, and the effect of man on the ecosystem. These are state-of-knowledge chapters. For example, there are 114 pages on soil physical properties and their variability, 51 pages on earthworms, 81 on termites and 19 on ants. The chapter on the effects of fire runs to 50 pages, that on deforestation to 61 pages and that on tillage to 52 pages. The detailed treatment means that each chapter is worth consulting as a subject review, and each contains numerous references to the literature. The book includes very little on the maintenance of nutrient supplies and in this respect will disappoint some readers. It is also over-illustrated, including, for example, 7

Book reviews

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Figures and 5 Tables on the calibration of the neutron moisture probe. The reproduction of photographs is below the standard that might be expected in a book at this price. It will, however, be welcomed as a source book by all who are concerned with the development of stable farming systems in the tropics. It is to be regretted that the price is so high. A. Wild